FIOS DVRs are Dual Tuners.
You can watch and/or record Two live shows at the same time.
The negative is the DVR drive size. If you record HD you run out of space pretty quickly.
There is no built-in PIP capability with the Verizon STB's, such as you likely had with DTV, even though the remote has a PIP button. My old service, Dish, had a very nice model 622 DVR that had multiple PIP possibilities. I don't know if the rumored new DVR from Cisco/SA will have it either. Some on this forum use a workaround since most TV's today have their own native PIP feature. What you need there is a seperate signal source from the main STB you are using, such as another STB (several options), OTA, whatever, and input that second signal to an input on the TV. Use the TV menu to determine the "sources" for your PIP feature. That might do as a temporary solution. I do miss that PIP during football season.